Easy invisible ink
Using this funny technique, suitable for kids and adults, we could write a hidden message and then put it in a bottle and give it to someone special.
Using a cotton bud dipped in lemon juice, write your secret message on white paper and put it in a pretty empty bottle. You can add colored hearts to give a colorful and flamboyant touch (for example, using the punchers we suggested you here.)
To reveal the message, so you only have to heat the paper with a light bulb or hair dryer (at this step, please stand next to your children) and voila! Never been the detective was so easy!